On Fri, May 22, 2015 at 12:44 PM, kenatsun <kenat...@gmail.com> wrote: > I'm evaluating Rails (vs Django) for a new project. A requirement of this > project is that the Rails app(s) be able to work with a database > (PostgreSQL, in case that matters) whose schemas (table definitions) have > been created and, over time, will be modified independently of the Rails > app(s). > > Though I'm a newbie to Rails, it already seems to be that Rails' standard > mode of operation is: (1) Models are created and modified within Rails, and > then (2) Rails Migration creates and modifies the database table > definitions. > > What I need is the opposite sequence: (1) The database table definitions > are created and modified through tools external to Rails, and then (2) the > Rails models are created and modified to fit the database table definitions. > > So my questions are: > > 1. First and most important, is there a Gem (or some other tool in the > Ruby-Rails world) that can generate a model from a database table > definition?
If you have a table named "things", all you need is a file named e.g. thing.rb that contains class Thing < ActiveRecord::Base end That will give you access to all the fields of that table. > 2. If not, presumably one could use Rails on a pre-existing database by > manually editing the Rails models. Right? See above. > 3. If that's right, what are the requirements for the table designs to > enable them to work as viable Rails models? It seems that one requirement > is that each table have a sequence-assigned primary key named "id". Right? Not exactly. You do need a primary key, and it's *easiest* with an integer, and *easiest* if the name is "id", but not necessary; I've got an app using string ids based on a legacy db schema (from what was previously a Java app). > Any others? Depends on what you're trying to do. I'd suggest just trying it :-) The "schemas independently modified over time" part presages some future pain, I would think; make sure you have *really good* test coverage. HTH, and good luck. -- Hassan Schroeder ------------------------ hassan.schroe...@gmail.com http://about.me/hassanschroeder twitter: @hassan Consulting Availability : Silicon Valley or remote -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To unsubscribe from this group and stop receiving emails from it, send an email to rubyonrails-talk+unsubscr...@googlegroups.com. To post to this group, send email to rubyonrails-talk@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/rubyonrails-talk/CACmC4yBR8yXMgR6DmNZVt99BCZQ3wSOdnOmzZWDqubZJyvL0Pw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
